1. Field of the Invention
The present invention relates to pressure vessels and fixing a tube thereto. More particularly, the present invention relates to fixing a tube to a pressure vessel used in an air-conditioning system, such as an accumulator or receiver.
2. Description of the Prior Art
Presently known in the art of tubular connections to a pressure vessel is a mounting block or block joint. Prior art mounting blocks support one or more tubes and facilitate connecting the tubes to the pressure vessel. Prior art mounting blocks are typically attached to a top of the pressure vessel by bolts or screws. This prior art method is unnecessarily complicated and costly for connecting tubes to a pressure vessel.
In contrast, a more simplified prior art method is disclosed in U.S. Pat. No. 4,707,999 awarded to Ohta et al. Ohta et al. attempt to simplify the mounting block connection method by incorporating a block joint on a receiver housing that has inlet and outlet tubes detachably connected thereto. Accordingly, Ohta et al. disclose a receiver housing having a flat top with the block joint connected to an upper surface thereto. The block joint has an opening on one surface for receiving a tube and a protrusion on the opposite surface for insertion into an opening at the top of the receiver housing. Ohta et al. further disclose two methods of connecting the block joint to the top of the receiver housing. One method provides a screw socket into which a fixing bolt is screwed, securing the block joint to the receiver housing. An alternative method provides a bolt having a lock nut. The combination of the bolt and the lock nut fix the block joint to the top of the housing.
In addition, to attach accessories such as pressure switches and sight glasses to the receiver housing, Ohta et al. disclose a modified block joint and multiple block joints. The modified block joint and the multiple block joints are fixed to the top of the receiver housing in the same manner as described above, by a bolt and lock nut arrangement. A pressure switch or sight glass must communicate directly with the interior of the pressure vessel. Therefore, in prior art block joint arrangements like the one disclosed in Ohta et al., access openings to the interior of the vessel are required in addition to the openings for the inlet and outlet tubes.
Such sight glass and pressure switch accessories are desirable features of an air-conditioning system for trouble-shooting and maintaining the system. However, the modified block joint and multiple block joints disclosed by Ohta et al. are very costly and add unwanted complexity to the air-conditioning system because of the additional access openings required for communication with the pressure vessel and the additional mounting blocks required for maintaining the accessory connections.
An alternative to the above-described mounting block is a fluid direction tube and bracket assembly as disclosed in U.S. Pat. No. 5,071,172 to Gross. Gross discloses a flexible bracket having a plurality of fluid direction tubes. The entire assembly must be made of a flexible material such as thermoplastic or glass reinforced polymer resin to achieve the necessary flexing and bending required of the bracket for proper assembly. Gross further discloses a chamfered receiving bore that receives a matching chamfer on the bracket assembly. Flexing and stretching the bracket is necessary to ensure proper alignment between the fluid direction tubes and the receiving bores, and an airtight pressure fit holds the bracket assembly in the receiving bores.
The assembly disclosed above in Gross is directed to an automobile engine body or part thereof. It is questionable whether the pressure fit could withstand the excessive pressure an accumulator is exposed to. Also, the tubular connections must accommodate the harsh environment and excessive pressures of the liquid refrigerant and it is not likely that a flexible thermoplastic resin could withstand exposure to such a harsh environment.
Another alternative in U.S. Pat. No. 5,072,710 to Washizu discloses a fuel delivery rail assembly for supplying fuel to a plurality of fuel injectors in an engine. The assembly disclosed in Washizu is an elongated conduit having a rectangular cross section and a plurality of tubular sockets. The conduit and each tubular socket are connected by deforming an annular extension of the tubular socket about a wall opening of the conduit, or by deforming an annular projection from the wall opening in the conduit about an internal shoulder in the tubular socket. A seal member is disposed between the surface of the conduit and the socket to prevent fuel leaks.
Accordingly, the conduit and socket assembly disclosed in Washizu is such that the sockets are permanently attached to the conduit and the upper side of the socket is adapted to receive a tip of a fuel injector only. The conduit wall must have a flat surface for seating the socket on the wall and maintaining the sealing effect of the seal member. The socket disclosed in Washizu is not capable of connecting any other device other than a fuel injector and does not have the capability of mounting or maintaining tubular connections other than the socket itself.
Therefore, what is needed is a simple reliable means to connect tubes to a pressure vessel and at the same time accommodate accessories, such as valves, pressure switches, or sight glasses, without excessive modifications, multiple parts, or unnecessary complexity.